The present invention relates to a moving body measuring apparatus that measures movement information of a moving body, such as the movement velocity, the movement direction, and the orientation of a golf club head immediately prior to a golf club striking a golf ball during a golf swing, and the initial velocity, movement direction, and spin rate of a golf ball immediately after being struck by the golf club.
Methods and apparatuses for finding movement information, such as movement velocity and rotation amount by providing a plurality of cameras along a path of a moving body, and photographing the moving body to measure the movement thereof (motion and behavior) have been heretofore proposed.
For example, JP 8-304020 A discloses a moving body movement-accuracy measuring apparatus that measures the amount of movement and the direction of movement of a moving body simultaneously, and performs evaluation of angular deviations of the moving body with little influence of errors in initial settings.
Further, JP 2002-525613 A discloses a method and an apparatus for measuring the flight path and the flight of a golf ball by using two cameras. With this method and apparatus, irradiation light is irradiated onto a reflective marker provided to a moving body that is an object to be measured, and light reflected by the reflective marker is photographed as an image. The irradiation light from an irradiation light source is reflected by using a total reflection mirror, and irradiated onto the reflective marker on a surface of the object to be measured. Holes are formed in the total reflection mirror in order to ensure the field of view for the two cameras. The cameras photograph the image through the total reflection mirror. In other words, the flight path and the flight of the golf ball are measured by making the optical axis of the irradiation light and the optical axis of the light reflected by the reflective marker approach each other. The velocity, direction, and bearing of a golf ball immediately after the golf ball is struck, and the flight path of the golf ball can be computed.
However, the movement direction of the object to be measured is substantially limited with the invention disclosed in JP 8-304020 A. Accordingly, it is necessary to install position detector elements over a wide region in order to measure the movement information of a moving body as it moves while rotating, for example, the movement information of a moving body such as the golf club head or a golf ball. The invention disclosed in JP 8-304020 A is thus not suited to measuring the movement information of the moving body accompanying rotation.
Further, although the optical path of the irradiation light irradiated onto the reflective marker approaches the line of sight axis of the camera with the invention disclosed by JP 2002-525613 A, they do not substantially overlap. In particular, the optical axis of the irradiation light irradiated onto the reflective marker and the line of sight axis of the camera are greatly separated when the moving body is relatively close to the measuring apparatus. Accordingly, the periphery of a center region that is a region of interest to be photographed by the camera is directly irradiated with the irradiation light and thus becomes bright. Since the center region itself is irradiated with indirect light from the irradiation light, the center region becomes darker compared to the periphery thereof. The light reflected by the reflective marker positioned in the region of interest thus cannot be photographed at high contrast, and it becomes necessary to perform complex image processing in order to correct the photographed image. Further, depending upon the circumstances, image processing may not be enough and the movement information of the moving body thus cannot be found.